Breech mechanism for automatic firearms



Aug. 9, 1960 F. UNDER BREECH MEGHANISM Foa AUTOMATIC FIREARMS n MZ., i

Aff/s United States Patent O BREECH MECHANISM Fon AUTOMATIC FmEARMsFriedrich Linder, zdrieh, switzerland, assigner te Md-V chine Tool WorksOerlikon, Administration Company, Zurich-Oerlikon, Switzerland, acompany of Switzer-l land Filed Feb. 3, 195s, ser. No. 112,813 Claimspriority, application Switzerland Feb. 7, 1957 1 Claim. (cl. s9-1s3) Thepresent invention relates to a breech mechanism for automatic firearms,and has theprimary objects of providing a breech mechanism inV which theinertia mass is divided into two parts, the rear part of which isaccelerated at a higher rate than the forward part, resulting in asmaller total inertia mass than in pure breech mass locked breechmechanisms and dispensing with a gas drive therefor, and at the the sametime providing a safe abutment for the bottom of the cartridge whenfired. It is another important object of the invention to provide -abreech mechanism o f the kind referred to, wherein the locking of thebreech is abolished at the moment only, when the projectile has left thebarrel and the pressure in the barrel has dropped to a value which It isyet another important object of the invention to provide a breechmechanism of the kind referred to which is suitable also for medium andlarge caliber automatic weapons. v

With these and other objects in view, I provide a breech mechanism forautomatic fire arms, comprising in combination: a barrel, a breech headtakingrthe thrust of the bottom of the cartridge fired, a rear breechportion, locking means therefor, said rear portion being slidablelongitudinally and-the said locking means being moveable transversely ofthe axis of the said barrel, and a locking tongue extending axially fromthe said rear portion towards said breech he'ad and engaging with playsaid locking means, said breech headbearing through said locking meanson roof-like -inclined faces stationary relative said barrel and oninclined faces directed transversely thereof on said rear portion,whereby said breech` head when recoiling accelerates said rearportionjatanl increased rat-io, said locking means after initial transversemovement owing to backsliding of the said breech head, is locked duringpart of the rearward movement of the said rear portion and thereby inturn interlocks the said breech head rigidly with the said barrel.

A breech mechanism according to the invention is not affected by theinavoidable fluctuations in the pressure rise within the cartridge inthe course of time after priming. It is also safeguarded against reboundphenomena occurring in the breech which in known breech mechanisms didnot provide with certainity that the components of the breech are at themoment of the shot development at a completely closed position and atrest. This danger may be countered by reboundpreventing means, whichhowever in their known embodiments are only rebound-damping orrebound-delaying devices by which the element of danger set forthhereinabove is only reduced but not completely eliminated.

This uncertainty, which is disquieting to the gunner, was also thereason why one had not yet dared to provide automatic weapons of mediumor large caliber with such known breech mechanisms. With ammunition ofsmall caliber weapons delayed burning after priming ocdoes not mean anymore danger to the cartridge case.

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curs to a far lesser extent than with larger calibers, since the primingcharge ignites the comparatively small charge at once and uniformly.However, the larger the charge, themore uneven the ignition thereof andthe higher the` danger of burst cartridge cases.

These difficulties have been successfully overcome by the presentinvention. In order that the same and its various details and featuresmay be clearly understood" and readily carried into effect, twoembodiments thereof will now be described by way of example withreference to the accompanying drawings, in which for cl-arity only thosecomponents are illustrated, which are essential for the understanding ofthe invention, and wherein:

lFig. 1 Iis a vertical section of a breech according to the invention.

Fig. 2 is a horizontal section of a first embodiment of the breechlocked by means of abutment aps, in the priming position,

Fig. 3 shows the breech according to Fig. 2 in the portion 4 of thebreechfforces the breech as a wholeinto the priming position shown inFigs. 1 and 2. On the breech head 2 an extractor l3 is fixed and in thelocking tongue 9 of Ithe rear portion 4 of the breech a percussion pin 5is pivoted by means of a pin 14, said percussion pin reaching through abore 15 of the breech head 2. The rear portion 4 of the breech transmitsthe pressure through the face 4d on to the breech head 2, which `in thepriming position abuts in turn the faces 10b of the casing 10.Rearwardly the breech head 2 bears through two abutment flaps 8 oninclined faces 10a of the casing 10. These abutment flaps 8 are forcedby the inclined faces-4a of the rear portion 4 of the breech into aswung-out position (conf. Fig. 2). A cartridge casing 11 inserted intothe barrel 1 bears on the face 2a of the breech head. The scar 7 servesin the usual manner for retaining the breech in the cocked' position inthat it abuts the inclined face 4e of the rear the usual manner,whereafter the cartridge casing forces the breech head 2 rearward. Thisthrust is transmitted by the abutment ilaps 8 to the inclined faces 10aon the casing 10, and since these inclined faces are not selflocking andthe faces of the flaps 8 opposite to the faces 4b of the lock-ing tongue9 do not contact these latter faces but stand at a distance from them,the abutment iiaps 8 will tend to give way inwardly. In this way, in thebattery position there is no positive locking of the breech head; thelock-ing action is assumed only by the combined mass of the two breechportions 2 and 4. By the inward movement of the abutment iiaps 8 theyimpart to the rear portion y4 of the breech through the inclined faces4a of the latter a rearward acceleration, until the abutment flaps 8 in`an intermediate position come into contact with the two parallel faces4b of the lock- Patented Aug. 9, 1960 ing tongue 9 of the rear portion 4of the breech while stillcontacting the faces a (see Fig. 3). Duringthis operation the breech head 2 has moved rearward a short stretch but`is restrainedyfrom further movement by` the abl'itrnent-ilapsVcontacting the two parallel faces 4b of the.v

lockingftongue 9. The breech head is .thereby/:positively locked.

The rear portion 4 of the breech continues its movement owing to itsinherent kineticY energy,` until the support of the abutment aps by thetwo parallel faces 4b of the locking tongue 9 at lits forward end isabolished andthe abutment aps 8 under the inuence of the thrust Vof thered cartridge swing further inwardly, wherebyy the positive lock-ing ofthe breech ,head` is abolished. The breech components then assume theunlocked position of Fig. 4. The rear portion 4 of the breech, bytheabutmentface 4c then carries along also the breech head, the returnmovement of the rear portion of the breech and of the breech head inunisonbeing eectivelfy assisted by the remainder ofthe gases in thebarrel.

During` the recoil of the breech the spent cartridge case is ejected inthe usual manner by the ejector 3 from the barrel, and the closurespring is loaded, which after the rear reversal of the breech throws thesame again forward, whereby a new cartridge is'supplied from themagazine or belt. After the breech head 2 having abutted the faces 10bof the casing, the locking of the breech is eifected in the reversesequence ofthe unlockingl thereof. The inclined faces 4f (Fig. 4) of thelocking tongue 9 spread the abutment aps 8 out, so that.

the same assume again their original. locking position.

head against the weapon casing may alternatively be elected by lockingmeans of a different kind, such asc for example by the slider blocks 12shown in Fig. 5. The manner of functioning of these slider blocks correfsponds exactly to that of the abutment flaps 8 of thev Figs. 2 to 4.y

The embodiments illustrated show the breechesl each having two lockingmeans 8 or'12, respectively; Nothing` would be changed in the substanceof the invention if only one-such locking means were used. Likewise it:is:

possible to build in more such locking means, for exe ample three oreven four ofthem.

Other obvious modifications may occur to a personVV skilled in the art,and I. wishto be understood` that I do'notlimit myself to the particulardetails and dimensibnsfof the preferred embodiments hereindescribed-andl illustrated.

What I claim as my invention and desire to secure by Letters Patent, is:

A breech mechanism for an automatic firearm, comprising in combination areceiver substantially extending along -a longitudinal axis of saidfirearm, sa-id receiver comprising a iirst abutment faceinclined to saidaxis; a two-parti' breechbloclo'. movably. guidedy =in saidA receiver,including a breech headloadedby the rearward thrust ofl adiredcartridge` and reciprocable between a battery breech mass-lock position,a recoiled. position. and an intermedia-te positivelockposition,` saidbreech Ablock furf ther includingV a rear breech portion comprising asecond abutment face inclined to said axis and a locking tongue with aforwardrend,said= tongue extending axially from saidfurtherabutrnentface toward.- said breech head; .a recoil spring engaging saidrear breech` portion to bias said breech blocktowardthessaid batterybreech mass lock position; locking means movably arranged in saidreceiver. and engaging said breech head, said locking means in saidbattery breech mass lockingposition beingV spaced from4said'locking'tongue and simultaneouslyiengaging both' said abutmentfaces, said locking means in said' intermediate positivelockpositionfurther simultaneously engaging said first' named abutment'face and saidtongue, saidlocking means upan a rearward movement of said breech headout' of 'said' battery breechmass looking position caused' bytheVthrustof a fired cartridge effectinga sliding movement along said rstabutment face towards saidntermediate, positively locked position,therebyxdiminishing said spacing, and simultaneously etfectinga furtherslidingv movement along said second abutment facertoimpant a recoilingmovement to saidl -rear breech portion, said locking means slidinglduring;

said recoilin'g movement' along said tongue up to said forward end` andthereupon becoming disengaged from said tongue, and saidlockingmeans'uponv reaching said forward end'of said tongue under the influenceof the thrust of `a red cartridge becoming disengaged from said first'abutment face thereby to unlock said breech head.

References Cited in theflile lof'this patent UNITED STATES PATENTS OTHER-REFERENCES Grossfuss German application Ser. No. G 11,355 Jil/72h;Iuneil'l, 1,956 (KL. 72h, 203).

Stecke Aug. 10, 1937

